Excess charged and deposited - Goods and Services Tax - GST

Dear Sir, we are a supplier to Railways; in 2022 we supplied materials to them but charged wrongly excess amount without giving the agreed discount amt. Now the bills are being processed for payment, but the customer his calculated as per the agreement, which is below our invoice value. We have deposited GST, but now customer is calculated GST at lesser amount. Accordingly, can we submit a revised invoice and claim back the excess GST deposited. with warm regards Arun Kumar